How to compile an INSERT ... ON DUPLICATE KEY UPDATE with SQL Alchemy with support for a bulk insert.

upsert.py

#!/usr/bin/env python
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"""
This module provides an "Upsert" statement for SQL Alchemy which uses 
ON DUPLICATE KEY UPDATE to implement the insert or update semantics. It
supports doing a bulk insert.
"""

import sqlalchemy as sa
from sqlalchemy.ext.compiler import compiles

class Upsert(expr.Insert): pass

@compiles(Upsert, "mysql")
def compile_upsert(insert_stmt, compiler, **kwargs):
    if insert_stmt._has_multi_parameters:
        keys = insert_stmt.parameters[0].keys()
    else:
        keys = insert_stmt.parameters.keys()
    pk = insert_stmt.table.primary_key
    auto = None
    if (len(pk.columns) == 1 and
            isinstance(pk.columns.values()[0].type, sa.Integer) and
            pk.columns.values()[0].autoincrement):
        auto = pk.columns.keys()[0]
        if auto in keys:
            keys.remove(auto)
    insert = compiler.visit_insert(insert_stmt, **kwargs)
    ondup = 'ON DUPLICATE KEY UPDATE'
    updates = ', '.join(
        '%s = VALUES(%s)' % (c.name, c.name)
        for c in insert_stmt.table.columns
        if c.name in keys
    )
    if auto is not None:
        last_id = '%s = LAST_INSERT_ID(%s)' % (auto, auto)
        if updates:
            updates = ', '.join((last_id, updates))
        else:
            updates = last_id
    upsert = ' '.join((insert, ondup, updates))
    return upsert

http://hackthology.com/how-to-compile-mysqls-on-duplicate-key-update-in-sql-alchemy.html

where did the expr defined?

import sqlalchemy.sql.expression as expr

Could you write one example how to use it?

I tried session.execute(AppPackage.table.upsert(),values) but it is not working..

session.execute(Upsert(table, items_list)) should do it.

can you amplify the example with code that doesn't use Sessions ? I'm not using the ORM API so I don't think I can use session objects.

Here's a concrete example, using a 'users' table with 3 columns, id is primary key
ins = users.insert().values(name='jack', fullname='Jack Jones', id=999)
res = conn.execute(ins)

and I'd like to use Upsert to change that record, say to
(name='snoopy', fullname='clever dog', id=999 )

nothing I've tried so far has worked.

I modified this slightly to account for unicode strings and easier imports:

import sqlalchemy
## SQLAlchemy Insert or Update for sessions, w00t!
class Upsert(sqlalchemy.sql.expression.Insert):
    pass
from sqlalchemy.ext.compiler import compiles
@compiles(Upsert, "mysql")
def compile_upsert(insert_stmt, compiler, **kwargs):
    if insert_stmt._has_multi_parameters:
        keys = insert_stmt.parameters[0].keys()
    else:
        keys = insert_stmt.parameters.keys()
    pk = insert_stmt.table.primary_key
    auto = None
    if (len(pk.columns) == 1 and
            isinstance(pk.columns.values()[0].type, sqlalchemy.Integer) and
            pk.columns.values()[0].autoincrement):
        auto = pk.columns.keys()[0]
        if auto in keys:
            keys.remove(auto)
    insert = compiler.visit_insert(insert_stmt, **kwargs)
    ondup = 'ON DUPLICATE KEY UPDATE'
    updates = ', '.join(
        '{} = VALUES({})'.format(c.name, c.name)
        for c in insert_stmt.table.columns
        if c.name in keys
    )
    if auto is not None:
        last_id = '{} = LAST_INSERT_ID({})'.format(auto, auto)
        if updates:
            updates = ', '.join((last_id, updates))
        else:
            updates = last_id
    upsert = ' '.join((insert, ondup, updates))
    return upsert

Here's a usage example:

from sqlalchemy.pool import NullPool
config['engine'] = sqlalchemy.create_engine(
            'mysql://{}:{}@{}:{}/{}'.format(
                                            config['user'],
                                            config['password'],
                                            config['host'],
                                            config['port'],
                                            config['database']),
            poolclass=NullPool
)
config['metadata'] = sqlalchemy.MetaData(config['engine'])
config['tableObj'] = sqlalchemy.Table(config['table'], config['metadata'], autoload=True)
config['connection'] = config['engine'].connect()
config['connection'].execute(Upsert(self._config['tableObj'], record))
# You can do multiple executes here over many objects. They won't auto-commit until close().
config['connection'].close()

That code doesnt take into account any special formatting for column names in the updates section. Something like the following might be an improvement for cross-compability:

    updates = ', '.join(
        '{} = VALUES({})'.format(preparer.format_column(column(c.name)), preparer.format_column(column(c.name)))
        for c in insert_stmt.table.columns
        if c.name in keys
    )

How to get the returning id?

FYI, I found another gist to do the upsert.

I'm getting the following error:
AttributeError: 'Upsert' object has no attribute '_has_multi_parameters

What type is the values object that we pass in? I was trying with a dict.